EP0833142B1 - Cryo-microtome - Google Patents

Description

The application concerns a cryostat microtome or a Microtome cryostat with one cryostat chamber and one in the Cryostat chamber arranged microtome, comprising a Specimen holder and a cooperating knife holder.

Cryostat microtomes of the type mentioned at the beginning have been around known for a long time and are commonly used to Preparations to cut thin slices, which are then under one Microscope to be analyzed. The cryostat microtomes point to this a cooled cryostat chamber in which a Specimen holder for holding a specimen to be cut and a knife holder movable against the specimen holder with a knife attached to it Preparations cut the said slices. The cooling is required to prepare preparations prepared by freezing to cut. The optimal temperature of the cut Specimen is usually determined empirically and is for different preparations depending on the preparation consistency differently. The cooling of conventional cryostat microtomes with cryostat chamber was done in different ways and Wise.

In a cryostat microtome shown in US 4,548,051, the as just described, the cooling is carried out by a central cooling device that controls the air in the Cool the cryostat chamber until the preparation to be cut has reached the appropriate temperature.

WO 87/02130 also shows one described above Cryostatic. The cooling takes place here via a central cooling device in which the air temperature of the Cryostat chamber is cooled, as well as additional cooling on the specimen holder in the form of a Peltier element, via one Fine control of the temperature of the preparation to be cut can be made.

There are also known from the prior art microtomes that work in ambient air and not in a cryostat chamber are located. Because here the knife and the preparation are not like in a closed cryostat chamber through a central one Cooling can be cooled is located in the Specimen holder as well as a cooling device in the knife holder, over which the specimen holder and the knife holder can be cooled. With such microtomes the Knife holder and thus the knife to a fixed predetermined Temperature cooled while the temperature of the preparation in Specimen holder is adjustable. Such cryostat microtomes do not usually reach particularly low temperatures because the warm ambient air warms the microtome too much.

US 3495490 A and WO 88/02851 include microtomes Freezers and open cooling systems known in which one liquid coolant evaporates in open containers. Are there separate evaporation containers also on the specimen holder and on Knife holder provided. With the help of additional electrical The heaters on the knife holder and the specimen holder are the Temperatures of the knife holder and the specimen holder independently adjustable. The disadvantage of these is known systems, however, the consumption of coolant with the associated operating costs.

The object of the present invention is to begin with designated cryostat microtome with cryostat chamber with propose improved properties.

The object is achieved according to the features of claim 1.

The basic idea of the invention is that both the temperature of the specimen holder, as well as the temperature of the Knife holder are adjustable independently of each other. Under the term adjustable should be understood to mean that the Temperature in a temperature range can be selected by the user, and then the temperature according to the selected temperature a control mechanism is set.

This results in a number of special advantages. It It has been shown that the quality of a cut is next to the temperature of the preparation is also considerably different from that Temperature of the knife depends. Due to the separate adjustability the temperature of the knife holder and therefore of it attached knife can therefore cut the specimen can be significantly improved by for the specimen holder and the knife holder the optimal temperature that can be different for knife and specimen. There also like cryostat microtomes with a cryostat chamber not yet known, cooling directly on the Knife holder, the room temperature must be in the cryostat chamber are nowhere near as low as this with conventional cryostat microtomes with a cryostat chamber was required. This results in particular Advantage that in addition to reduced energy consumption Cooling the chamber also sizing the cooling device can be greatly reduced, which is a reduced size of the entire microtome cryostat. In addition, the Microtome cryostat significantly faster than previous microtome cryostats with a cryostat chamber, because the Knives and the specimen do not first reach room temperature must be cooled, but both cooled immediately are.

For temperature control of the specimen holder and the knife holder there are different possibilities Consideration. The cooling control can be in the form, for example a well-known two-point controller take place in which cooling after falling below the set temperature is switched off and after exceeding the set Temperature is switched on again. The setting of the However, temperature can also be set by the knife holder and the specimen holder can be cooled and heated independently of one another are.

One way to do this is, for example, that Cooling and heating in the specimen holder or in the knife holder Peltier element is provided, with Peltier elements in Dependence on the technical direction of the current to the Peltier element applied voltage either heat or cool. To cool the Peltier element should also be in the knife holder and in the specimen holder small, to a cooling device connected evaporator may be provided.

Because the temperature of the knife is usually not that low must be dimensioned as the temperature of the to be cut Specimen can be placed in the knife holder instead of the Peltier element in contrast to this, an electrical one that is cheaper Heating element to be installed, for setting and / or Regulate the temperature of the knife holder against the temperature of the evaporator is counter-heated.

Although the cooling of the specimen holder and the knife holder mainly done by the evaporators attached to it, it is nevertheless advantageous to add an additional one in the cryostat chamber Provide evaporator that the air temperature in the Cryostat chamber lowered. The air temperature to be provided here in the cryostat chamber, however, unlike conventional ones Cryostats with a cryostat chamber far above the temperature of the preparation to be cut or the knife.

To the energy required to cool the microtome as possible to be kept low and thus also the dimensioning of the cooling device To make it as low as possible should be as possible few parts of the microtome are provided in the cryostat chamber be so that only a few parts have to be cooled and also the Cryostat chamber can be kept small. Furthermore should also include electronic components that cause warming could contribute to the cryostat chamber, such as electric motors etc. arranged outside the cryostat chamber become. The microtome is then partially inside and partially located outside the cryostat chamber. In order to ensure that between those inside the cryostat chamber lying parts and the outside of the cryostat chamber Share as little cold as possible and at the same time to ensure the highest possible stability of the microtome, should be in the transition area between those inside the cryostat chamber lying parts of the microtome and the outside of the Parts of the microtome lying exclusively in the cryostat chamber Components made of VA steel are used.

The cryostat microtome can be used particularly advantageously if the specimen holder and the knife holder are in very cooled down to the set working temperature for a short time become. This is particularly possible when in the cooling device two cooling circuits are provided, the second cooling circuit to which the evaporators in the specimen holder and connected in the knife holder, via a coaxial heat exchanger through a first cooling circuit is pre-cooled.

Further advantages and developments of the invention result from the drawings.

Figur 1

eine rein schematische Seitenansicht des Kryostatmikrotoms;

Figur 2

einen Teilschnitt durch das Kryostatmikrotom gemäß Figur 1;

Figur 3

ein Blockschaltbild der Kühleinrichtung von Mikrotomen gemäß Figur 1.

Show here:

Figure 1

a purely schematic side view of the cryostat microtome;

Figure 2

a partial section through the cryostat microtome according to Figure 1;

Figure 3

2 shows a block diagram of the cooling device of microtomes according to FIG. 1.

Figure 1 shows a purely schematic side view of the Cryostat microtome according to the invention, from the next to the outline of the cryostat microtome only the division of the cryostat microtome evident. The reference number (1) is used here Designated cryostat chamber, with (57) the chamber for receiving the electronic control and regulation components and with (56) the Chamber for holding important components of the cooling device.

Figure 2 shows a partial section not drawn to scale a cryostat chamber (1) with a microtome arranged therein (2) an inventive cryostat microtome according to FIG. 1, the presentation is essentially based on the pure mechanical components of the microtome (2) limited and Details such as electrical lines, connections the cooling device etc. largely left aside were. The microtome (2) comprises a coolable one Specimen holder (4) on which the specimen to be cut (5) is attached. To cool the specimen holder (4) is in Specimen holder (4) a small evaporator (7) is provided via connections (50, 51) to one described below Cooling device is connected. The Little Vaporizer (7) provides a temperature that cannot be further regulated, so that additionally a Peltier element (6) on the evaporator (7) is applied with depending on the current direction of a current applied to it additionally cooled or heated can be. This allows the temperature of the Specimen holder very fine according to the requirements of the Adjust the preparation to be cut (5).

The microtome (2) also has a coolable knife holder (8) on. The knife holder (8) is used for this a knife (9) or a disposable blade, the Preparation holder (4) with the preparation (5) attached to it the cutting edge of the knife (9) or the disposable blade around thin slices of the preparation (5) to cut off. The exact mechanics for performing the said cutting process will be explained further below are explained.

To cool the knife holder (8) is in the lower area Knife holder (8) also one via connections (12, 13) to one Cooling device provided evaporator (10) provided likewise the knife holder (8) and thus the knife (9) a sufficiently long time to a large extent constant temperature value cools down. Because the achievable Temperature for all selectable temperatures of the knife (9) or the blade is sufficient to adjust the temperature just below the evaporator in the knife holder (8) Electric heating element (11) is provided. To set the The temperature of the knife holder (8) is simply the heating output the heating element (11) until the knife holder (8) has the desired temperature.

Thus both the temperature of the specimen holder (4) and also the temperature of the knife holder (8) regardless of mutually adjustable. To set the temperature are the Knife holder (8) and the specimen holder (4) are independent of this one another via the evaporators (7, 10) or the Peltier element (6) coolable, and also via the Peltier element (6) and Heating element (11) heatable. Both in the knife holder (8) and In the specimen holder (4) there is a temperature sensor (36, 37) provided by which the current temperature of the Specimen holder (4) in the area of the specimen and that of Knife holder (8) is measured separately in the area of the knife. By means of a control device, not shown, the Temperatures of the specimen holder (4) and knife holder (8) the respectively preset, for specimen holder (4) and Knife holder (8) generally different target temperatures adjusted in such a way that the temperature sensors (36, 37) recorded temperature measurements of the respective target temperature correspond. The temperature in the cryostat chamber itself will however, not regulated separately.

The exact mechanics will now be described below with reference to FIG of the microtome, via which the specimen holder (4) and thus the preparation (5) arranged thereon on the knife (9) of the Knife holder (8) is moved past. To cut the Specimen (5) becomes the specimen holder (4) accordingly the double arrow (14) moves up and down. This is the Specimen holder (4) between two side parts (15), of which only one is shown here and which form a chassis, in Movable in the direction of the arrow (14). The side parts (15) each have a V-shaped groove on their inner wall (17), in the one not shown here on the specimen holder (4) attached rollers run. The roles are here Specimen holder (4) arranged such that it alternates one roll each on one leg of the V-groove and one the roller underneath runs on the other leg of the V-groove etc. Such guides are known to the expert Cross roller guide known and should not be discussed here are explained. On the back of the specimen holder (4) there is a horizontal groove (19) which the opening and Movement of the specimen holder (4) is used. In the groove (19) a sliding block guided horizontally. A head start (20) of a lever (22) on a rotatable shaft (21) engages in a hole through the sliding block. When the shaft rotates (21) results from the horizontal component of movement of the lever (22) a horizontal movement of the sliding block in the groove (19) and from the vertical component of movement of the lever vertical movement of the specimen holder (4).

As can be seen from Figure 2, the shaft (21) over a drive (25) located outside the cryostat chamber (1) in Rotation offset. For this purpose, the shaft (21) is rotatable in one Sleeve (23) guided the insulating wall (24) of the cryostat chamber (1) breaks through. Said drive (25) can here, how this is shown in Figure 1, in the form of an electric motor be designed or in the form of a handwheel gear, by a handwheel attached to the side of the cryostat microtome is driven.

The infeed of the knife (9) in the direction of the arrow (16) is done as follows. So the knife holder (8) is on two successive tubes (26), of which only this rear is shown, via corresponding guides in the sleeves (27) movably guided in the direction of arrow (16). As well as visible here, the knife holder is in the Cryostat chamber (1) while the other end of the tubes (26) is located outside the cryostat chamber (1). To move the Knife holder (8) in the direction of arrow (16) connects here a bridge (28) the pipes (26), being in the middle of the bridge a mother not shown here is provided. The The nut is connected to a threaded spindle (52) in turn is driven by a stepper motor (47). to Displacement of the knife holder (8) in the direction of the arrow (16) the stepped motor (47) simply turns said threaded spindle (52) rotated so that then on the threaded spindle screwed nut of the bridge (28) along the arrow (16) is moved back and forth. Of course, the position of the Stepper motor (47) and the mother can also be interchanged, so that the stepper motor (47) is then on the bridge (28) and the mother then sits where the stepper motor (47) in FIG. 2 is arranged.

The microtome itself is on the sloping back wall of the Cryostat chamber arranged so that the direction of movement for the Infeed movement of the knife holder diagonally upwards or downwards he follows. At the same time, the installation height is chosen such that between the lowest microtome components and the bottom of the Cryostat chamber a free space of 5 to 10 cm remains, making the cryostat chamber easily cleaned of debris can be.

In addition, a lamella evaporator (29) in the Cryostat chamber (1) pointed out in addition to the in Knife holder (8) and arranged in the specimen holder (4) The evaporator also evaporates the air temperature of the cryostat chamber (1) cools down. Since the knife holder (8) and the specimen holder (4) can be cooled separately, however, the finned evaporator (29) be dimensioned relatively small because the air temperature in the cryostat chamber (1) no longer the temperature of the Specimen holder (4) or the knife holder (8) must correspond. While with conventional cryostat microtomes the air temperature the cryostat chamber can be cooled down to -55 ° or even -60 ° had, it is enough for the cryostat microtome according to the invention Cool the air temperature to -20 °. The knife holder can then at an air temperature of -20 ° a temperature of -35 ° assume and the specimen holder (4) can even by Peltier element (6) are cooled down to -55 °. As before As stated above, this results in an energy saving, which is in a much smaller dimensioned cooling device and of course a lot less dimensioned cryostat microtome. As another Advantage of direct cooling of the specimen holder (4) and the Knife holder (8) shows that higher air temperatures in the cryostat chamber (1) is less detrimental to the cut quality impact; therefore also the distance of the microtome extraordinarily low to the upper edge of the cryostat chamber be interpreted, which in turn benefits ergonomics.

To further reduce the necessary cooling capacity, the Cryostat chamber (1) over a cryostat wall (24) good thermally insulated. The cryostat wall (24) consists of one VA sheet steel tray (30), which has a good heat insulation Foam layer (32) is surrounded. In addition, the Cryostat chamber (1) through a plastic not shown here or covered with glass. In addition, they became big Parts of the microtome (2) outside the cryostat chamber (1) arranged so that on the one hand the cryostat chamber (1) as possible becomes small and, on the other hand, as few parts of the microtome as possible are also to be cooled. Furthermore, in particular electronic components, such as the stepper motor (47) or the drive (25) outside the cryostat chamber (1) arranged to heat up by those of these components to avoid radiated waste heat. Because the microtome (2) partially inside and partly outside the cryostat chamber (1) is arranged, are also in the transition area between the Components and arranged within the cryostat chamber (1) the components arranged outside the cryostat chamber (1) of the microtome (2) only VA steel is used. The Rods (26), the sleeves (27), the shaft (21) and the sleeve (23) are thus made of VA steel. Choosing this Materials has the particular advantage that one hand Material with a very low thermal conductivity is used is, on the other hand, a very high rigidity having.

To further increase the rigidity of the entire microtome (2) increase, the sleeves (27) and the sleeve (23) are over bridges (33, 34, 35) continues to stiffen.

The cooling device of the cryostat microtome is now to be illustrated with reference to FIG are explained, parts of which are in the Cryostat chamber (1) and other parts are in the chamber (56) of the cryostat microtome (see FIG. 1). Strictly speaking the cooling device shown is two cooling circuits (43, 44) connected in series, at which a first cooling circuit (43) is used for pre-cooling and a second cooling circuit (44) then via the evaporators (7, 10) in the specimen holder (4) and in the knife holder (8) as well as over the Finned evaporator (29) is running. The first cooling circuit (43) has a condenser (39) which is connected via a throttle (42) or a capillary runs in a coaxial heat exchanger (38) and via a compressor (37) back into the condenser (39) running back. In the coaxial heat exchanger (38), the first cooling circuit (43) the coolant for the second Pre-cooled cooling circuit (44) to be described. The Coaxial heat exchanger (38) acts for the first cooling circuit like an evaporator by the evaporating coolant cools the second cooling circuit (44). The second cooling circuit (44) is structured similarly to the first. Here too are, as usual with chillers, chokes (40, 41) or Capillaries are provided, the output of which is then carried out with the lamella evaporator (29) and the evaporator (10) in the knife carrier (8) is connected or to the evaporator (7) in the specimen holder (4). The outputs of the evaporators (7, 10) are also included a compressor (36) connected to the compressed, vaporous The coolant then pumps back into the condenser (39). The two-part cooling circuit just described has the particular advantage that the second cooling circuit (44) is already pre-cooled. As a result, the cryostat chamber (1) or the cryostat microtome (2) within a relatively short time the working temperature can be cooled. You can also do that Cryostat microtome (2) thereby relatively easily in a stand-by mode switch in which only the cooling circuit (43) to Pre-cooling of the coaxial heat exchanger (38) runs. The cooling circuit (44) can be switched off in stand-by mode.

The evaporators (7, 10, 29) are therefore part of one Cooling circuit having a coaxial heat exchanger (38).

In addition, the cooling circuit is designed so that the condenser (39) and at least one of the Compressors (36, 37) at the level of the cryostat chamber (1) located behind the cryostat chamber (1). This has the special one Advantage that a relatively compact cryostat microtome is created that is easily portable and unproblematic can be placed on a table.

It should also be noted that the evaporator (7) in the specimen holder on the one hand and the evaporator (10) in the knife holder and the Lamellar evaporator (29) on the other hand in two connected in parallel Sub-circuits of the second cooling circuit (44) are arranged, each having its own throttle (40, 41). As a result, compared to single-circuit cooling circuits, where all evaporators are connected in series, less printing problems. It also results from the separate sub-circuit for the evaporator (7) in Specimen holder a lower minimum temperature. Since the Temperature of the knife and the cryostat chamber usually are higher than the preparation temperature associated evaporator (10, 29) connected in series. Under However, accepting a somewhat larger effort can also be accepted the partial circuits for all three evaporators must be separate and each have their own choke.

The cryostat microtome can also advantageously have connections have with which this is coupled to external additional devices can be. For example, the knife holder has one here only partially shown suction device (55) on the Cutting waste when cutting the to be cut Preparations (5) are suctioned off. To use this Setup can, for example, on the bottom of the Cryostat microtome with the suction device (55) connected, not shown here provided connection to which a device generating a negative pressure is connected, by its negative pressure the cut waste sucks through the suction device (55) on the knife holder (8) become. It is also conceivable that on the bottom of the cryostat microtome a connection for a disinfection device is provided, via which the cryostat chamber of the Cryostat microtome is disinfected.

In conclusion, it should now be mentioned that the invention is by no means is limited to the embodiment shown here. Rather, all modified embodiments are also intended be included, for example, the cooling circuit as a single cooling circuit can be arranged so that the Throttle (42) of the coaxial heat exchanger (38) and the compressor (37) can be omitted. Likewise, too for example, the mechanics of the microtome (2) are completely different be carried out to carry out the cutting movement.

Claims (7)

1. Cryostat microtome, having a cryostat chamber (1), a microtome (2) which is arranged in the cryostat chamber (1) and comprises a coolable specimen holder (4) and a coolable blade holder (8), it being possible to set both the temperature of the specimen holder (4) and the temperature of the blade holder (8) independently of one another, the blade holder (8) and the specimen holder (4) having small evaporators (7, 10), characterized in that the evaporators (7, 10) each have an inlet (12, 50) for a liquid coolant and an outlet (13, 51), and in that the outlets (13, 51) are connected to a compressor (36) which pumps gaseous coolant to a liquefier (39).
2. Cryostat microtome according to Claim 1, in which the blade holder (8) and the specimen holder (4) can be cooled and heated independently of one another in order to set the temperature.
3. Cryostat microtome according to Claim 2, in which a heater element (11) is provided in the blade holder.
4. Cryostat microtome according to Claim 3, in which an evaporator (29) is additionally provided in the cryostat chamber.
5. Cryostat microtome according to Claim 1, in which the microtome (2) is arranged partially inside and partially outside the cryostat chamber (1), exclusively VA steel being used in the transition region between those components of the microtome which are arranged inside the cryostat chamber and those components of the microtome which are arranged outside the cryostat chamber.
6. Cryostat microtome according to Claims 1-5, in which the evaporators (7, 10, 29) are part of a cooling circuit (43, 44) which has a coaxial heat exchanger (38).
7. Cryostat microtome according to one of Claims 1-6, in which the evaporator (7) of the specimen holder (4) and the evaporator (10) of the blade holder (8) are arranged in separate partial cooling circuits, which each have a dedicated throttle (40, 41).

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